Dag Schanke

Fischer-tropsch synthesis on monolithic catalysts of different materials

Monolithic structures made of cordierite, γ-Al 2 O 3 and steel have been prepared as catalysts and tested for Fischer-Tropsch activity. The monoliths made of cordierite and steel were washcoated with a 20 wt.% Co-1 wt.% Re/γ-Al 2 O 3 Fischer-Tropsch catalyst whereas the γ-Al 2 O 3 monoliths were made by direct impregnation with an aqueous solution of the Co and Re salts resulting in a loading of 12 wt.% Co and 0.5 wt.% Re. The activity and selectivity of the different monoliths were compared with the corresponding powder catalysts. Higher washcoat loadings resulted in decreased C 5+ selectivity and olefin/paraffin ratios due to increased transport limitations. The impregnated γ-Al 2 O 3 monoliths also showed similar C 5+ selectivities as powder catalysts of small particle size (38-53 μm). Lower activities were observed with the steel monoliths probably due to experimental problems.

Fischer-Tropsch synthesis on cobalt catalysts supported on different aluminas

Alumina with different surface area has been prepared by heat treatment of γ-alumina. Improved C5+ selectivity was obtained by using Co or CoRe supported on low surface area alumina (LSA, 15 m2/g). LSA alumina resulted in the lowest Co dispersion and in reduced activity for secondary hydrogenation of propene.

Fischer-Tropsch synthesis using monolithic catalysts

Abstract Cordierite monoliths have been washcoated with a 20 wt. % − 1 wt. % Re/γ-alumina Fischer-Tropsch catalyst and tested for Fischer-Tropsch activity. The activity and selectivity were comparable to the corresponding powder catalyst at low washcoat loadings. Higher washcoat loadings resulted in decreased C5+ selectivity and olefin/paraffin ratios due to increased transport limitations. Impregnated alumina monoliths with a Co loading of 12 wt. % (and 0.5 wt. % Re) also showed similar C5+ selectivity as the small-particle powder catalyst. A large-particle powder catalyst (425-850 lIm) showed very low C5+. selectivities due to severe intraparticle transport limitations.

Optimisation of Fischer-Tropsch Reactor Design and Operation in GTL Plants

Abstract By using examples from fixed-bed and slurry bubble column reactors using supported cobalt Fischer-Tropsch catalysts, the influence of key process parameters on reactor performance is illustrated. It is shown that there is a strong coupling between reaction kinetics, intraparticle / interphase mass-transfer and reactor characteristics which, together with other process parameters, will determine the overall reactor performance.

Scale-up of Statoil's Fischer-Tropsch process

Publisher Summary This chapter describes the major elements of Statoils Fischer–Tropsch (F–T) technology and the current efforts within scale-up and commercialization. To maximize distillate production from subsequent hydrocracking of the F–T wax, a low temperature, cobalt catalyst based technology has been selected. It is generally accepted that a slurry bubble column reactor offers the best performance in terms of economy of scale, throughput, and yield, but also presents several technical challenges both regarding catalyst properties and critical details of the reactor design. To achieve the desired reactor productivities, a highly active cobalt catalyst is needed. In addition, the catalyst must be adapted to suit the requirements of the slurry reactor. Statoil has discovered that addition of small quantities of rhenium or certain other metals to alumina-supported cobalt catalysts will increase the activity significantly. The chapter illustrates the effect of Re showing that the effect of Re is most pronounced at small loadings and then levels out at higher amounts of Re.

Resolving flow details in slurry bubble columns used for Fischer-Tropsch synthesis using computational fluid dynamics

Publisher Summary Computational fluid dynamics (CFD) has been used as a design tool for single-phase flows for past several years. The use of CFD for multiphase systems still is in a developmental phase. Multiphase CFD has been used to simulate some laboratory systems where detailed information about the flow is known. This has contributed to further develop and improve the simulation models. The main providers of CFD software are also developing their codes to be able to handle problems of commercial interest. However, there is still need for further development of the models. Information about the large-scale flow in large columns cannot be readily obtained by direct measurements. Design is based on extrapolating the knowledge of the flow in smaller systems. By using CFD it is possible to gain more information about the flow. Such increased knowledge can be used to increase productivity and/or reduce costs. CFD can also be used to investigate details of the flow in regions of specific interest, for example, the gas distributor region, the outlet areas, and around specific internals. This chapter presents simulations performed using the commercial codes CFX and Fluent.